In 1575 the Poles choose as their king Stephen Báthory, who has made his name in central Europe as commander of the Transylvanian army and then as the elected prince of Transylvania. He marries the last princess of the Jagiellon dynasty (the sister of Sigismund II).

Stephen's eleven years on the Polish throne bring many successes to Poland, particularly in the campaign against Russia - where the border is pushed steadily northwards in successive campaigns. For his armies Stephen skilfully harnesses the energies of Poland's wild men from the southeast, the Cossacks. He also encourages the talents of another large minority within Poland, the Jews.

Appreciating the value of the skills of the Jews, Stephen Báthory takes special steps to protect their interests - restricting, for example, the trading rights of merchants and pedlars arriving in Poland at this time in large numbers (rather surprisingly) from Scotland.

He also grants the Polish Jews their own parliament, which meets twice a year and has tax-raising powers. It remains in existence for nearly two centuries, till 1764.

Vasa kings of Poland: 1587-1669

After the death of Stephen Báthory without an heir, the Poles elect in 1587 Sigismund III, a member of the Vasa dynasty of Sweden. His father is John III of Sweden; his mother is a Polish princess, sister of Sigismund II. Brought up in his mother's faith as a Catholic, Sigismund fails to hold the Lutheran throne which he inherits in Sweden.

He and his two sons rule Poland for nearly a century, until 1669. For much of that time the branches of the Vasa family, in Poland and in Sweden, are at war with each other. The Polish Vasas do considerably less well for their kingdom than their cousins on the Swedish throne..

Poland, which includes Lithuania, has two neighbours of comparable stature, with each of whom there is constant likelihood of warfare - Russia to the northeast and Muslim powers to the southeast, consisting of Tatars in the Crimea and the Ottoman Turks. Between these groups, in the Ukraine, are the unpredictable Cossacks.

At the start of the Vasa period the Cossacks, though always unruly, are for the most part loyal to Poland - the kingdom within which their Ukrainian territory lies. But high-handed behaviour by Polish landowners and religious discrimination (the Cossacks are Greek Orthodox, the Poles Catholic) prompt a great Cossack rebellion in 1648.

At times during this period the Cossacks unite with the Tatars against Poland, at other times with the Russians. In the long run their actions damage themselves as much as the Poles. By the truce of Andruszow, in 1667, all the Cossack territory to the east of the river Dnieper is transferred from Poland to Russia. With it goes the ancient city of Kiev.

In addition to loss of territory, Poland is weakened during the Vasa period by an increasingly unworkable political system. The parliament, or sejm, now makes a fetish of the ancient right of any single deputy to veto legislation simply by exclaiming Nie pozwalam (I disapprove). The business of state virtually grinds to a halt.

John III Sobieski: 1674-1696

In the century after the Vasa dynasty (which ends with the death of John Casimir in 1668), Poland continues in a gradual and ultimately fatal decline. The process is hastened by two wars which rage around and across the kingdom - the Northern War and the War of the Polish Succession. It leads eventually to the partition of the country in the late 18th century.

But there is one outstanding moment of glory during the reign of John III Sobieski, in 1683, when the Polish king saves Vienna and Christendom from the Turks.

Vienna and Hungary: 1683-1718

On 31 March 1683 a huge Turkish army marches west from Edirne. On the same day, in Warsaw, the Polish king John III Sobieski signs a treaty committing him to bring a force to the defence of Vienna. There is panic in the Austrian capital as the Turks approach, with a force estimated to be about 250,000 strong. Early in July the emperor and his court abandon Vienna, slipping away to safety higher up the Danube. A few days later the invading army arrives to blockade the city.

Two months pass before John III arrives with his Polish contingent, reinforced by Catholics from Bavaria and by Protestants from Saxony. The Christian army amounts to about 70,000 men.

The attack on the Turkish force takes place on September 12. After eight hours of fighting the Turks are routed and the city relieved. It is a symbolic moment which also proves a turning point, inspiring the Austrians to transform the retreat of the Turks into a lasting withdrawal.

Further campaigns to the east result in the capture of Buda in 1686, followed by the gradual recovery of other parts of Hungary. By 1699 the Turks are willing to sign the peace of Karlowitz, ceding to the Habsburg emperor, Leopold I, the whole region of Hungary which has been under Turkish control since 1547 - apart from the small area of Banat in the extreme southeast, which remains with the Turks until 1718.

Poland and Saxony: from1697

John III Sobieski dies in 1696. Poland, a hereditary kingdom during the Vasa dynasty, has reverted to being an elective monarchy. On this occasion nineteen candidates put themselves forward - to the great benefit of the members of the sejm, among whom the candidates' agents distribute lavish bribes.

The winner of the contest is Augustus II (known as Augustus the Strong), the elector of Saxony. A significant factor in his favour is his late arrival on the scene. He comes with a fresh supply of funds when those of his rivals are already exhausted. The most recent bribe is the most vivid. But the decision, made in 1697, is a bad one for Poland. Augustus views his new kingdom as an accessory to Saxony.

In 1699 Augustus makes a secret alliance with Denmark and Russia for a joint attack on the Swedish territories round the Baltic. His own target is Livonia, which he intends to acquire for Saxony (his new Polish subjects refuse to cooperate in the enterprise). In February 1700 Augustus marches north with a Saxon army to besiege Riga.

His action launches the long Northern War against Sweden. But in spite of his own resounding name, Augustus the Strong more than meets his match in 1700 in the young Charles XII of Sweden.